1. Field of the Invention
Exemplary embodiments of the present invention relate to a sheet adjusting device for adjusting a sheet to a given position on a sheet setting plate, a sheet holding receptacle including the sheet adjusting device, an image forming mechanism including the same, and an image reading mechanism including the same.
2. Description of the Related Art
Known related-art apparatuses that handle sheet-like recording media such as image forming apparatuses (copiers and printers), image reading apparatuses (scanners), and automatic document feeders (ADFs), have a sheet adjusting device for adjusting a sheet such as a recording sheet (including an overhead projector (OHP) film, and document sheets, etc.) to a given position in a direction perpendicular to a sheet conveyance direction. For example, certain related-art image forming apparatuses include the sheet adjusting device in each sheet cassette or on each manual feed tray. Further, the scanners and the ADFs are also known to include such a sheet adjusting device on a document setting table on which original document sheets are placed preparatory to being read.
Typically, in related-art sheet adjusting devices, two opposed side fences serving as regulating members are provided to regulate a sheet placed on a sheet setting plate or a document setting table to adjust the position of the sheet. One side fence regulates one side edge of the sheet and the other side fence regulates the other side edge of the sheet. At least one of these side fences is slidably movable. Before inserting a sheet stack into a sheet setting tray or a document setting table, an operator slides the side fences manually to the edges of the sheet setting tray to create space for the sheet stack. The width between the edges of the sheet setting tray can be greater that the width of the sheet stack. After the sheet stack is inserted into the space formed between the side fences, the operator slides the side fences manually to securely sandwich the sheet stack from either side therebetween. Since the operator presses the side guides lightly against a sheet or sheets that differ from a reference sheet position on the sheet setting plate, the position of the sheet stack can be adjusted to the reference sheet position.
Different known related-art sheet adjusting devices have a configuration including of a combination of the above-described sheet adjusting device and a structure including a drive source and a drive transmission mechanism to drive the side fences so as to slide the side fences automatically. For example, Japanese Patent Application Publication No. 07-267474 (JP-H07-267474-A) discloses the above-described combined configuration to center a sheet stack set on a manual feed tray in a direction perpendicular to the sheet conveyance direction of the manual feed tray.
Although these related-art sheet adjusting devices adjust a sheet easily, the sheets are easily scratched or damaged. Specifically, in the process of pressing the sheet stack on the sheet setting plate to the reference sheet position, the sheet is slidably pressed by the side fences, which can damage the sheet. In addition, when a large number of sheets is loaded on the sheet tray, the whole weight of the sheet stack presses on a lowermost sheet thereof so as to press down on the sheet setting plate of the manual feed tray, and therefore a surface of the lowermost sheet and a surface of a contact face that faces the surface of the lowermost sheet can be scratched or damaged easily. Further, when a coated sheet such as glossy paper for printing thereon is used, even if only one sheet is slid on the sheet setting table, sliding over the sheet setting plate can generate small scratches on the surface of the sheet due to abrasion of the sheet surface.
Further, sheet folding and damage to the sheet can be generated, for example, when the side fences slide on the sheet setting plate to move the sheet to the reference sheet position. In this process, the leading edge of the sheet may contact the end fence disposed to regulate the leading edge of the sheet. If the side fences are slidably moved in this condition, the sheet can be folded or torn.